The present invention relates to an improvement of a method for operating a general-purpose two-cycle internal combustion engine to be operated under predetermined conditions and a two-cycle internal combustion engine itself best adapted for carrying out the above method.
Two-cycle diesel engines and two-cycle spark ignition engines have been long used as general purpose power sources under constant or predetermined conditions for generating an electric power, pumping water, driving a fan and so on. The diesel engines are most advantageous in the fuel economy, but the compression ratio is higher and because of their heavy weight it is difficult to relocate them from one place to another. Furthermore the combustion noise and vibration are so high that they are not suitable for use in the urban areas and especially in the residential areas. In addition, the diesel engines need a fuel supply system including a fuel injection pump, fuel injection valves which are operated under high pressures. Thus in terms of maintenance and cost the diesel engines are disadvantageous.
Spark ignition engines are lighter in weight and operate at a relatively low compression ratio. However it is difficult to concentrate a fresh charge around the spark plug. Furthermore the combustion is not stable because of misfire, and sometimes the fresh air-fuel mixture is short circuited to flow out of the combustion chamber. As a result, the fuel economy cannot be attained and the emission of a large quantity of HC results.